Apparatus for preparing hollow plastic articles

ABSTRACT

The apparatus of the present invention involves transferring plastic parisons from a receiving station to a finishing station on a plurality of pallets in a single row for forming said parisons into hollow plastic articles. The pallets with parisons thereon are transported through a temperature conditioning means for temperature conditioning said parisons to render same suitable for forming into said hollow plastic articles at the finishing station.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part of copending U.S. patentapplication Ser. No. 648,793 by Robert D. Schad, filed Sept. 7, 1984,now U.S. Pat. No. 4,522,581, patented June 11, 1985.

BACKGROUND OF THE INVENTION

Our present invention relates to a method and apparatus for producing,by injection or compression molding (collectively referred to aspressure molding), partly finished workpieces which are transferredsequentially to one or more aftertreatment stations for the performanceof secondary operations thereon. In particular, the workpieces may beparisons of polymeric material and the secondary operations may be athermal conditioning thereof followed by their transformation intohollow articles, such as containers, by blowing with or withoutmechanical stretching.

A system for conveying parisons or preforms by means of pallets into andout of a blow molding station has been described in U.S. Pat. No.4,426,202 to Krishnakumar et al. According to that patent, the parisonsor preforms presumably molded at a remote location are carried in groupson rotatable collets of roller-supported pallets which move on a trackto the blow molding station where each parison is introduced between twoopen mold halves, subsequently closing therearound for transforming sameinto bottles. During the blow and briefly thereafter, the parisons andthe bottles formed therefrom remain attached by their necks to thecollets of their pallets which, however, do not otherwise participate inthe blow molding operation. On the contrary, as expressly stated in thepatent, the support of the preforms, i.e. the engagement of theirflanges for holding them in position, is transferred from the pallet tothe blow mold during the blowing operation. Nothing is said about whereor how the pallets, which are separated from their track after the blow,are loaded and unloaded.

A major object of the present invention is to provide an improved methodand apparatus for the continuous recirculation of a sufficient number ofpallets between a receiving station, at which they are to be loaded withworkpieces yet to be finished, and one or more aftertreatment stationsfor further handling and finishing.

Another object is to provide a method and apparatus as aforesaid inwhich the loading of the pallets with newly arriving workpieces, theirtransportation to the aftertreatment stations, their handling in thelatter stations and the return of the pallets to the receiving stationare precisely synchronized with one another and with the source of theworkpieces, e.g., an injection molding machine, to provide the desiredhigh degree of efficiency.

It is also an object of the present invention to provide an improvedpallet structure for a system of this type which enables accuratelocation and secure retention of each parison in a finishing station,particularly in a blow molding station in which it is inflated with orwithout the use of a stretching rod.

A more particular object of the present invention is to synchronize theoperation of a molding apparatus, specifically an injection moldingmachine, with those of a temperature conditioning and a blow moldingstation, having regard to the fact that an operating cycle of the latterstation is considerably shorter than that of an injection moldingmachine so that the difference in timing has to be taken into account.Since the overall number of available pallets will normally be limited,the present invention further aims at insuring a return of unloadedpallets to the loading point in time for having them receive the newlyarriving partly finished workpieces in keeping with the cycle of theinjection molding machine.

SUMMARY OF THE INVENTION

In accordance with the present invention the foregoing objects andadvantages, as well as others, may be readily obtained. The apparatus ofthe present invention is an apparatus for preparing hollow plasticarticles which comprises: a receiving station for receiving a firstnumber of plastic parisons; a finishing station for forming said plasticparisons into said hollow plastic articles; a first conveyor meansmoving from said first receiving station to said finishing station; asecond conveyor means returning from said finishing station to saidreceiving station; a multiplicity of pallets successively entrainable bysaid conveyor means in a single row, each of said pallets being providedwith holding means for holding a second number of parisons less thansaid first number; means to transfer said pallets from said finishingstation to said second conveyor means; means for transferring saidpallets from said second conveyor means one at a time to said receivingstation until said holding means at said receiving station correspondsto said first number; and means for transferring said pallets with saidparisons thereon one at a time from said receiving station to said firstconveyor means. A temperature conditioning means is provided adjacentsaid first conveyor means between the said receiving station andfinishing station for conditioning the temperature of the parisons torender same suitable for forming into said hollow plastic articles atsaid finishing station operative to condition the temperature of saidparisons to first equalize the temperature of said parisons and secondto obtain the desired temperature profile for forming into said hollowplastic articles.

The process of the present invention comprises transferring a pluralityof plastic parisons to a multiplicity of pallets at a receiving station;conveying said pallets with the parisons thereon in a single row fromsaid receiving station to a finishing station for forming said parisonsinto said hollow plastic articles; providing conditioning means betweensaid receiving station and finishing station for conditioning thetemperature of the parisons to render same suitable for forming intosaid hollow plastic articles at said finishing station; and transportingsaid pallets with parisons thereon through said temperature conditioningmeans in a single row to first equalize the temperature of said parisonsand second obtain the desired temperature profile for forming into saidhollow plastic article.

The pallets with parisons thereon are transferred from said receivingstation to said finishing station via a first conveyor means and theempty pallets are returned from said finishing station to said receivingstation via a second conveyor means, with the pallets transferred fromsaid second conveyor means to said receiving station one at a time untilthe desired number of pallets is present at said receiving station.After the parisons are loaded on the pallets, the pallets aretransferred from said receiving station to said first conveyor means oneat a time so that they can be moved from the receiving station to thefinishing station in a single row one at a time.

It is a particular advantage of the process and apparatus of the presentinvention that the output of an injection molding machine may becoordinated with the receiving station so that one can transfer a firstnumber of plastic parisons directly from an injection molding operationto the desired number of pallets at the receiving station. This iscoordinated with the finishing station so that the more rapid output ofthe blowing operation is not an impediment to the slower injectionoperation. The pallets are moved serially one at a time in a single rowfrom the receiving station to the finishing station where the finishingoperation is conducted on one pallet at a time. Correspondingly, thepallets pass through the temperature conditioning means in a single rowso that the temperature exposure in the temperature conditioning meansmay differ one pallet to the other. The present invention is suitablefor accommodating this differential temperature treatment withoutreduction in cycle time which represents a considerable advantage.Similarly, the returning pallets return to the receiving station in asingle file one at a time and are loaded in the receiving station one ata time until the desired number of pallets is present thereat. Thus, theentire cycle is carefully coordinated to maximize efficiency.

In an additional feature of the present invention the carrying means fortransferring the parisons from the injection molding means to thereceiving station may comprise a hollow tube having cooling meanstherein for post cooling the plastic parisons. Suitably, the hollow tubeis dimensioned with a slight taper so that the parison will not fitcompletely therein. Upon post cooling the parison the parison shrinkssomewhat so that the prison slides downward along the tapered wallretaining a good heat exchange relationship with the wall and ismaintained in its final position via suction or other means inside thetapered tube.

The process and apparatus of the present invention will be more fullydescribed hereinbelow together with additional advantages thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more readily apparent from a considerationof the following illustrative drawings wherein:

FIG. 1 is a perspective view of the apparatus of the present invention;

FIG. 1A is a top view of the apparatus of the present invention;

FIG. 2 is a cross-sectional view along the lines 2--2 of FIG. 1A;

FIG. 3 is a cross-sectional view along the lines 3--3 of FIG. 1A;

FIG. 3A is a perspective view of the pusher means shown in FIG. 3;

FIG. 4 is a cross-sectional view along the lines 4--4 of FIG. 1A;

FIG. 5 is an isometric view of the finishing station shown in FIG. 1A;

FIG. 5A is a schematic view of the finishing station;

FIG. 5B is a perspective view of the engaging means for moving thepallets into the finishing station and out of the finishing station;

FIG. 6 is a detailed view of the carrying means for conveying theparisons from the injection mold to the receiving station at one pointin the operation; and

FIG. 7 is a detailed view of the same carrying means for conveying theparisons from the injection mold to the receiving station at a laterstage in the operation.

DETAILED DESCRIPTION

The apparatus and process of the present invention in a representativeembodiment for transporting the parisons from the receiving station tothe finishing station and temperature conditioning same can be clearlyseen in FIGS. 1-4.

Referring to FIGS. 1 and 1A, first conveyor means 10 transports pallets11 from receiving station 12 to finishing station 13. The empty palletsare returned to the receiving station 12 via second conveyor means 14.Thus, as seen in FIG. 1A the first conveyor means moves from left toright and the second conveyor means moves from right to left. Theconveyor means preferably comprises a continuous chain or belt as shown,although separate, synchronized chain sections may be used. Sprockets15, 16 and 17 are shown engaging chain links 18 of the conveyor meansfor moving same in a rotary direction, see FIGS. 3 and 4. Thus, as shownin FIG. 1A, sprockets 15 and 16 move counterclockwise and sprocket 17moves clockwise so that the chain links and hence the conveyor means aretransported in a desired direction. Any desired motive means may beutilized to power any one or more of the sprockets so that, for example,one sprocket may be powered and the others may freely rotate. Chainguides 19 are provided around chain links 18 in order to guide same intheir path. Means are provided associated with the conveyor means andengageable with the pallets for pushing the pallets along the conveyormeans, such as pusher means 20 connected to chain links 18 which engagethe base of pallets 11 in order to push the pallets along their path.These can be clearly seen in FIG. 4.

The pallets 11 contain a desired number of parison holding means orplugs 30 for holding parisons 31 via the open neck thereof 32, withthree such plugs per pallet shown in the drawings. Pallets 11 comprise aplatform member 33 supporting parison holding means or plugs 30 whichare rotatably journaled to pulley means 34 beneath platform member 33 sothat the pulley means 34 and hence the plugs may be rotated in aclockwise or counterclockwise direction as desired. Any number ofparison holding means or plugs 30 may be selected for each pallet.Generally, the number of plugs per pallet will correspond to the numberof blow molds at the finishing station to be described hereinbelow.Pallets 11 are guided by channel track 35 as they move on the conveyormeans.

The parisons are preferably delivered to the receiving station as theoutput of an associated injection molding machine, although otherparison preparation or delivery means may be used, for example,compression or extrusion molding. In the preferred embodiment as shownin FIGS. 1 and 1A, injection molding machine 40 prepares the appropriatenumber of parisons based on the capacity of the injection moldingmachine. Naturally, any desired injection molding configuration may beused. As shown in FIGS. 1 and 1A, the injection molding machine includesa fixed platen 41 and a movable platen 42. The movable platen moves ontie rods 43 via machine clamp 44. Mold means 45 are provided between thefixed and movable platen to prepare the desired number of parisons.Carrier means such as robot 46 are provided adjacent the fixed andmovable platen having track 47 for carrying robot arm 48 (see FIG. 2)which in turn carries robot plate 49. Robot plate contains adjacentthereto a number of parison carrying means 50 corresponding to thenumber of parisons prepared in the injection molding machine. Carryingmeans 50 are open ended hollow tubes having channel means 51 at the basethereof connected to vacuum or suction means 52 for holding the parisonsin the tubes. Thus, parisons are formed in injection molding machine 40,movable platen 42 disengages from the fixed platen 41 and robot arm 48carrying robot plate 49 moves between the fixed and movable platen sothat parison carrying means or tubes 50 engage parisons 31. Suctionmeans 52 is used to transfer parisons 31 from the injection moldingmachine to tubes 50 and retain the parisons therein. Robot plate 49 isthen moved out from between fixed platen 41 and movable platen 42 androtated so that robot plate 49 is placed adjacent receiving station 12as shown in FIG. 2. Parisons 31 are then delivered to pallets 11 byreleasing the suction from suction means 52. Parisons 31 are thenreleased so that the open neck portion 32 engages plugs 30 with guidetube 60 supported by support frame 61 insuring that the parisons areproperly directed to engage plugs 30. Referring to FIG. 2, it can beseen that the parisons 31 are properly seated on plugs 30. As shown inphantom in FIG. 2, open neck 32 indicates the position of the parison intubes 50.

After the parisons are loaded on pallets 11 the pallets are transferredone at a time from the receiving station to the first conveyor means 10.Simultaneously therewith, an empty pallet is transferred from the secondconveyor means to the receiving station. This operation can be seen inFIGS. 3 and 3A wherein pusher means 62 is provided above the level ofthe pallets having a pusher frame 63 and pusher rods 64 journaledtherein. Pusher frame 63 carries forward pusher arms 65 and rearwardpusher arms 66. The forward pusher arms 65 engage the pallet adjacentthe first conveyor means and the rearward pusher arms 66 engage thepallet on the second conveyor means. Upon activation of pusher 62 pusherarms 65 and 66 cooperate to move the pallet adjacent the first conveyormeans from the receiving station to the first conveyor means and thepallet from the second conveyor means to the receiving station. Thisoperation is continued until the pallets with parisons thereon are movedone at a time from the receiving station to the first conveyor means anduntil empty pallets from the second conveyor means are moved to thereceiving station so that the receiving station contains a series ofempty pallets corresponding to the product output of the injectionmolding machine. The parisons are then transferred from the injectionmolding machine to the empty pallets at the receiving station asdescribed hereinabove.

As indicated hereinabove, the initial step of the temperatureconditioning cycle for conditioning the parisons from the injectionmolding machine to the finishing station is the post cooling operationconducted in the parison carrying means or tubes 50. Preferably, theparison carrying means or tubes are provided with heat transfer meanswhich will be described in more detail hereinbelow in order to post coolthe still warm parisons from the injection molding operation.

The parisons are then transported from the receiving station 12 to thefinishing station 13 on first conveyor means 10. A temperatureconditioning means 70 is provided adjacent the first conveyor means 10so that parisons 31 can have their temperature properly conditioned ontheir path from the receiving station to the finishing station. Thepurpose of the temperature conditioning means is to condition thetemperature of the parison to render same suitable for forming intohollow plastic articles at the finishing station. The features of thepreferred temperature conditioning means can be clearly seen in FIG. 4.The plastic parisons 31 on pallets 11 pass through temperatureconditioning means 70 in a single row. The temperature conditioningmeans first equalizes the temperature of the parisons and second obtainsthe desired temperature profile for forming said parisons into hollowplastic articles. FIG. 4 shows conditioning tunnel 71 surroundingparisons 31 and containing temperature conditioning means 72 adjacentparisons 31. A plurality of such temperature conditioning means 72 areprovided along the length of the parisons in order to provide the exacttemperature profile needed by the parison in the finishing operation.The temperature conditioning means may be radiant or air jets and thesemay also be used to first equalize the temperature of the parisons. Theparisons arrive at the first conveyor means with an unequal distributionof temperature between the inside and outside thereof. Thus, it is thefirst stage of the temperature conditioning means to equalize thetemperature between the inside and ouside thereof by means oftemperature conditioning means 72 or if desired simply air jets in theinitial stage of the conditioning tunnel 71. After the temperature ofthe parison has been equalized, a plurality of temperature conditioningmeans 72 may be provided adjacent various points along the length of theparison in order to provide the exact temperature distribution desiredfor the particular plastic and particular bottle configuration. One canvery accurately control the temperature equalization and temperatureprofiling operation by controlling the length of the conditioning tunneland the temperature conditioning means, and this despite the fact theindividual pallets remain in the tunnel for different periods of time.Protective cover 73 is provided to protect the open neck portion 32 ofthe parisons so that the open neck portion is not subjected to thetemperature equalization step. Safety cover 74 may be provided on thereturn flight in order to protect the empty pallets. If one desires torotate the parisons during their passage through the temperatureconditioning tunnel, stationary belt 75 or other means may be providedadjacent and in contacting relationship with pulley means 34 thusrotating the pulleys and hence the parisons. The rotation may becontrolled by the speed of movement of the pallet, the diameter of thepulley and/or whether or not belt 75 is stationary or movable.

At the downstream end of the first conveyor means chain links 18 of thecontinuous chain pass around idler roll 80 and downstream sprocket 17and idler roll 81 to start the return flight along second conveyor means14.

Referring now to FIGS. 5, 5A and 5B, pallets 11 are retained in channeltrack 35 free from chain links 18 adjacent finishing station 13 carryingparisons 31 on plugs 30 ready for the finishing operation. Finishingstation 13 as shown in FIG. 5 includes fixed platen 82 and movableplaten 83 with blow mold 84 therebetween containing a mold 85 in theshape of the bottle to be formed. Movable platen 83 moves on tie rods 86activated by motor 87. Base mold 88 is held by support 88a and ispositioned above mold 85 to form the bottle bottom with piston 89connected thereto for moving the bottom mold into appropriate alignmentfor formation of the desired base for the bottle and motive means, notshown, connected thereto for activating said piston. Linkage means 90and 91 are provided connected to the movable platen 83 and bottom mold88, respectively, in order to maintain the desired positioning thereof.Channel track 92 slides on tie rods 86 and sits spaced from but closelyadjacent to channel track 35 being moved by top and bottom linkage means90 and 91. For better clarity of the drawings, only bottom linkage means90 is shown in FIG. 5. Engaging means 93 shown in FIGS. 1 and 5Bcomprises a piston 94 having a piston arm 95 with a first engaging lug96 engaging a groove 97 in an upstream pallet 11 and a second engaginglug 98 engaging a similar groove 97 in a downstream pallet 11. Firstengaging lug 96 and second engaging lug 98 are rotatable in thedirection of the arrow to engage and disengage grooves 97. Thus, inoperation first and second engaging lugs 96 and 98 are rotated to engagegrooves 97 on a pallet 11 sitting outside finishing station 13 and apallet sitting inside finishing station 13, respectively. The piston arm95 then moves forward to move the pallet inside the finishing stationwith blown bottles thereon to a position outside the finishing station13 and move a second pallet from a position outside the finishingstation to a position inside the finishing station. Second piston 99 isnow operated to rotate the first and second engaging lugs 96 and 98,respectively, to disengage grooves 97 and the piston arm is retracted toengage a further set of pallets for repeat of the cycle. Movable platen83 is closed. Bottom mold 88 is moved into position via piston 89 andthe blowing operation commenced. As shown specifically in FIG. 5A, aspace 100 is provided to permit air to be inserted inside the parisonalthough any other suitable means may be used for this purpose. Ifdesired, a plug can be activated to axially stretch the parison in orderto provide an oriented article and the parison is blown to its fullshape as shown in FIG. 5A. When the blow mold is opened channel track 92moves a desired distance guided by linkage means 90 in order to move thefinal blown article 102 the desired distance and free it from the mold85. The pallet 11 with finished articles thereon is then moved from thefinishing station to a point past or downstream of the finishingstation. Pusher means 112 is located downstream of the finishing stationconnected to piston 113 which may be connected to any desired motivemeans. Track 114 engages discharge station 110 with return station 115.Thus, in operation piston 113 positions the pallet 11 containing blownarticles 102 via pusher means 112 along tracks 114 to return station115. At return station 115 the empty pallets are moved to the secondconveyor means via second engaging means 116 which corresponds toengaging means 93. Located at return station 115 is discharge station110 used to remove finished articles 102 from pallets 11 via for examplea suction tube 111 or any desired means. The empty pallets are thentransferred to the second conveyor means at a rate exactly correspondingto the movement of the pallets in the first conveyor means and in thefinishing station. Although a particular engaging means has been shown,naturally any engaging means may be used to move the pallets in and outof the finishing station, and to move the empty pallets to the secondconveyor means.

If desired the process and apparatus of the present invention may beconveniently employed to prepare multi-layered hollow plastic articlesby applying a sleeve member either inside preform 31 or outside preform31, with the composite preform consisting of preform 31 and sleevemember heated in temperature conditioning means 70 and blown together.For example, a sleeve or liner member may be applied to plugs 30 ontheir return flight on second conveyor means 14. Thus, pallets 11 returnto receiving station 12 containing sleeve member thereon so that preform31 is applied over the sleeve member and the composite conditioned andblown together at finishing station 13.

Alternatively, a sleeve member may be applied on the outside of preform31 downstream of receiving station 12 but before temperatureconditioning means 70 so that the composite preform and sleeve memberare conditioned together in the temperature conditioning means 70 andblown together at the finishing station 13. The resultant multi-layeredarticle is characterized by properties of both materials, that is, thesleeve and preform, so that one can design a finished article having adesirable combination of properties not possible in a single layeredmaterial.

Referring now to FIGS. 6 and 7, these show a preferred form of parisoncarrying means. In past practice, the parisons were stripped into aguide tube and inside dimension of which was typically larger than thatof the parisons. The parisons were then supported on the shoulder of theguide tubes by suction within the guide tubes. Upon insertion of theparison into the guide tube internal pressure was applied within theguide tube causing the still pliable parison to expand against the wallsof the guide tube and thereby establishing heat transfer contact inorder to obtain cooling of the parison. A pressure differential betweenthe inside of the parison and the space between the outside thereof andthe guide tube can be established by applying higher than atmosphericpressure inside the guide tube or by applying vacuum therein. Naturally,this type of system can be readily used in combination with the presentinvention. However, it has been found that this type of system is notentirely successful since it is difficult to carry out and necessitatesaccurate and expensive locating means to place the parisons into theguide tubes.

According to a preferred practice of the present invention, carryingtube 50 is provided with a cavity 11 having tapered walls as, forexample, a taper of 0 degrees, 25 minutes, 30 seconds, the taper thereofbeing the same as the taper of the parison. Parisons are normallytapered in order to facilitate removal from the injection mold. Themouth dimension of carrying tube 50 is chosen so as not to permit theparison to fill cavity 120 completely. Instead, at the time ofinsertion, a small portion of the parison will protrude from carryingtube 50. Carrying tube 50 is provided with temperature control meansschematically indicated by channels 121 which can be connected to anysource of heat transfer fluid. Suction channel 122 is provided forremoval of air from cavity 120 during insertion of the parison and isused to apply vacuum within cavity 120. It is seen that parison 31 willmake contact with the inner mold wall due to the taper but only to theextent that the opening of the guide tube will permit. As the parison 31cools in contact with the guide tube wall due to the pressuredifferential established between the atmosphere inside the parison andthe vacuum applied through channel 122, it is reduced in size andtherefore slides downward along the tapered wall of the guide tube. FIG.7 is a schematic sectional view which shows the parison in its finalposition. Thus, it can be seen that the cooling effect due to surfacecontact between the parison and the guide tube is in this instance givenby a taper which, of course, is also an automatic locating means forcentering the parison in the cavity. Accordingly, in this improved postcooling mold, there is no need for expensive locating devices in thecooling process. It is automatically accomplished by virtue of thedimensional change which occurs in the parison in the course of cooling.

This invention may be embodied in other forms or carried out in otherways without departing from the spirit or essential characteristicsthereof. The present embodiment is therefore to be considered as in allrespects illustrative and not restrictive, the scope of the inventionbeing indicated by the appended claims, and all changes which comewithin the meaning and range of equivalency are intended to be embracedtherein.

What is claimed is:
 1. An apparatus for preparing hollow plasticarticles said apparatus comprising: a receiving station for receiving afirst number of plastic parisons; an injection molding machine in spacedrelationship to said receiving station for injection molding said firstnumber of plastic parisons in an injection molding cycle for transfer tosaid receiving station and means for transferring said first number tosaid receiving station; a finishing station for forming said plasticparisons into said hollow plastic articles; a first conveyor meansmoving from said receiving station to said finishing station; a secondconveyor means returning from said finishing station to said receivingstation; a multiplicity of pallets successively entrainable by saidfirst and second conveyor means in a single row, each of said palletsbeing provided with holding means for holding a second number ofparisons less than said first number, wherein said pallets are operativeto transfer said plastic parisons from said receiving station to saidfinishing station; means to transfer said pallets from said finishingstation to said second conveyor means; means to transfer said palletsfrom said second conveyor means one at a time to said receiving stationuntil said holding means at said receiving station corresponds to saidfirst number; means for transferring said pallets with said parisonsthereon one at a time from said receiving station to first conveyormeans; and means for transferring said pallets with said parisonsthereon one at a time from said first conveyor means to said finishingstation to form hollow plastic articles.
 2. An apparatus according toclaim 1 including a temperature conditioning means adjacent the firstconveyor means for conditioning the temperature of the parisons torender same suitable for forming into said hollow plastic articles atsaid finishing station operative to condition the temperature of saidparisons to first equalize the temperature of said parisons and secondto obtain the desired temperature profile.
 3. An apparatus according toclaim 1 including post-cooling means between the injection moldingmachine and receiving station for post-cooling the parisons.
 4. Anapparatus according to claim 1 including means associated with theconveyor means and engageable with the pallets for pushing the palletsalong the conveyor means.
 5. An apparatus according to claim 1 includingmeans associated with said holding means for rotating the holding meansand parisons held thereon.
 6. An apparatus according to claim 2 whereinsaid temperature conditioning means is a temperature conditioning tunnelthrough which the parisons pass from the receiving station to thefinishing station.
 7. An apparatus according to claim 1 including meansfor transferring said pallets with parisons thereon one at a time fromsaid first conveyor means to said finishing station, and means forsimultaneously transferring said pallets with hollow articles thereonone at a time from said finishing station to a discharge station.
 8. Anapparatus according to claim 1 including means to transfer empty palletsone at a time from said second conveyor means to said receiving stationand means for simultaneously transferring said pallets with parisonsthereon one at a time from said receiving station to said first conveyormeans.
 9. An apparatus according to claim 3 including carrying means fortransporting said parisons from said injection molding machine to saidreceiving station provided with heat transfer means to post-cool theparisons from the injection molding machine.
 10. An apparatus accordingto claim 9 including means for maintaining the cooled parison inside thetube.
 11. An apparatus according to claim 2 wherein said temperatureconditioning means includes a plurality of temperature conditioningdevices along the length of the parisons to provide an exact temperatureprofile at the finishing station.
 12. An apparatus according to claim 2wherein said parisons have an open neck portion and wherein saidtemperature conditioning means includes means to protect the neck fromsaid temperature conditioning means.
 13. An apparatus for preparinghollow plastic articles said apparatus comprising: a receiving stationfor receiving a first number of plastic parisons; an injection moldingmachine in spaced relationship to said receiving station for injectionmolding said first number of plastic parisons in an injection moldingcycle for transfer to said receiving station and means for transferringsaid first number to said receiving station; a finishing station forforming said plastic parisons into said hollow plastic articles; a firstconveyor means moving from said receiving station to said finishingstation; a second conveyor means returning from said finishing stationto said receiving station; a multiplicity of pallets successivelyentrainable by said conveyor means in a single row, each of said palletsbeing provided with holding means for holding a second number ofparisons less than said first number; means to transfer said palletsfrom said finishing station to said second conveyor means; means totransfer said pallets from said second conveyor means one at a time tosaid receiving station until said holding means at said receivingstation corresponds to said first number; means for transferring saidpallets with said parisons thereon one at a time from said receivingstation to first conveyor means; and means for transferring said palletswith said parisons thereon one at a time from said first conveyor meansto said finishing station to form hollow plastic articles, including apost-cooling means between the injection molding machine and receivingstation for post-cooling the parisons, carrying means for transportingsaid parisons from said injection molding machine to said receivingstation provided with heat transfer means to post-cool the parisons fromthe injection molding machine, wherein said carrier means comprises anopen ended tube having a taper corresponding to the taper of the parisonbut somewhat smaller than the parison so that said heat transfer meansis operative to shrink the parison upon cooling with the parison slidinginside the tube to fit snuggly therein.